The drives on which the above mentioned boxes are used, require often further devices - such as engagement and disengagement devices torque limiting devices unindirectional couplings (i.e. freewheels), flexible couplings, spontaneous or driven slip clutches, and other - which are usually autonomously inserted within the drive. This brings about significant overall dimensions, construction complications (for the need to protect the device elements inside their own seal case) and application problems, possibility of increased risks with respect to the personnel safety, higher costs and other drawback which are evident to those skilled in the art.